I remember reading about your loss Silvercat, and it spawned more discussions about what happens to our deceased pets. I have horses myself, so understand how you felt. I'm also a Pagan, and I found the following link for you, but quite honestly, I don't know anyone who've ever followed the words that you'll see. Go to the spot where your horse was, and imagine him as he was when he was with you. Ask the 4 elements to care for him and for the Goddess to protect his spirit. Then stand on the spot, and wait. As you're thinking, you'll probably see or feel something wonderful to let you know that you've been heard. Blessings.